1. Field of the Invention
The present invention relates to a head-up display used in a vehicle such as a motor vehicle.
2. Description of the Background Art
A head-up display projects a display image of a display device on a projection surface such as a windshield positioned in front of a driver's seat. A virtual image is displayed anterior to the windshield to a driver. Therefore, a driver can visually recognize the display image without widely moving his/her eyes.
Japanese Utility Model Application Laid-Open No. 63-164038 (1988) discloses a head-up display provided with first and second display devices, a half mirror, and a housing which houses the first and second display devices and the half mirror inside thereof. By using this head-up display, in front of a driver, two virtual images which are formed at different positions from each other are displayed so as to overlap with an outside view in front of a windshield. However, since the two virtual images are displayed to be parallel to each other, there is a problem in that the displayed image is planar and has no stereoscopic effect.
On the other hand, in a head-up display disclosed in Japanese Patent Application Laid-Open No. 2007-264529, an angle of a first display device and an angle of a second display device with respect to a half mirror are made different from each other so that displayed angles of two virtual images are different from each other, thereby displaying an image having a stereoscopic effect.
However, the head-up display of Japanese Patent Application Laid-Open No. 2007-264529 requires two display devices in order to display a stereoscopic image. Further, it is necessary to set the angle of each of the display devices. Therefore, there is a problem in that the structure of the head-up display is made to be complicated.